Imaging lens and imaging apparatus including the imaging lens

ABSTRACT

An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a negative refractive power and has a meniscus shape which is concave toward the object side, a third lens that has a meniscus shape which is convex toward the image side, a fourth lens that has a positive refractive power and is convex toward the object side, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fixed-focus imaging lens that formsan optical image of a subject on an imaging device, such as a chargecoupled device (CCD) and a complementary metal oxide semiconductor(CMOS), and to an imaging apparatus, such as a digital still camera, acellular phone with a camera, a mobile information terminal (PDA:Personal Digital Assistance), a smartphone, a tablet terminal, and amobile game machine, on which the imaging lens is mounted to performphotography.

2. Description of the Related Art

As personal computers have become popular in homes, digital stillcameras which are capable of inputting image information aboutphotographed scenes, persons, and the like into the personal computershave spread rapidly. Further, a cellular phone, a smartphone, or atablet terminal in which a camera module for inputting images isinstalled has been increasing. Such apparatus having an imaging functionuses an imaging device, such as a CCD and a CMOS. Recently, because theimaging device has been miniaturized, there has been also a demand tominiaturize the whole of the imaging apparatus and an imaging lensmounted thereon. Further, since the number of pixels included in theimaging device has also been increasing, there has been a demand toenhance the resolution and performance of the imaging lens. For example,there has been a demand for performance corresponding to high resolutionof 5 megapixels or higher, and preferably performance corresponding tohigh resolution of 8 megapixels or higher.

To satisfy such demands, it can be considered that the imaging lens iscomposed of five or six lenses, which are a relatively large number oflenses. For example, Japanese Patent No. 4858648 (Patent Document 1) andJapanese Patent No. 4792605 (Patent Document 2) propose an imaging lenscomposed of five lenses. The imaging lens disclosed in Patent Documents1 and 2 substantially consists of, in order from an object side, fivelenses of a first lens that has a positive refractive power, a secondlens that has a negative refractive power, a third lens that has apositive refractive power, a fourth lens that has a positive refractivepower, and a fifth lens that has a negative refractive power.

SUMMARY OF THE INVENTION

In particular, for the imaging lenses used in apparatuses, of which thethickness has been decreased, such as a cellular phone, a smartphone ora tablet terminal, a demand to decrease the total length of the lens hasbeen increased more and more. Hence, it is necessary to further decreasethe total lengths of the imaging lenses disclosed in Patent Documents 1and 2.

The present invention has been made in view of the above-mentionedcircumstances and an object thereof is to provide an imaging lenscapable of achieving high imaging performance in the range from thecentral angle of view to the peripheral angle of view while achieving adecrease in the total length thereof. Another object of the presentinvention is to provide an imaging apparatus capable of obtaining aphotographed image with high resolution through the imaging lens whichis mounted thereon.

The imaging lens of the present invention is an imaging lenssubstantially consisting of, in order from an object side, five lensesof:

-   -   a first lens that has a positive refractive power and has a        meniscus shape which is convex toward the object side;    -   a second lens that has a negative refractive power and has a        meniscus shape which is concave toward the object side;    -   a third lens that has a meniscus shape which is convex toward        the image side;    -   a fourth lens that has a positive refractive power and is convex        toward the object side; and    -   a fifth lens that has a negative refractive power and has at        least one inflection point on an image side surface.

According to the imaging lens of the present invention, in the imaginglens which is composed of five lenses as a whole, a configuration ofeach lens element of the first to fifth lenses is optimized. Therefore,it is possible to achieve a lens system that has high resolutionperformance while decreasing the total length thereof.

In the imaging lens of the present invention, the expression“substantially consisting of five lenses” means that the imaging lens ofthe present invention may include not only the five lenses but also alens which has substantially no refractive power, optical elements, suchas a stop and a cover glass, which are not a lens, mechanism parts, suchas a lens flange, a lens barrel, an imaging device and a hand shake blurcorrection mechanism, and the like. When the lens includes an asphericsurface, the reference sign of the surface shape and refractive power ofthe lens is considered in a paraxial region.

In the imaging lens of the present invention, by employing andsatisfying the following desirable configuration, it is possible to makethe optical performance thereof better.

It is desirable that the imaging lens of the present invention furtherinclude an aperture stop that is disposed on the object side of anobject side surface of the second lens.

In the imaging lens of the present invention, the third lens may have apositive refractive power.

In the imaging lens of the present invention, the third lens may have anegative refractive power.

It is desirable that the imaging lens of the present invention satisfiesany of the following conditional expressions (1) to (8).

It should be noted that, as a desirable mode, any one of the conditionalexpressions (1) to (8) may be satisfied, or an arbitrary combinationthereof may be satisfied:−2<f/f345<−0.25  (1),−1.8<f/f345<−0.3  (1-1),0.2<(R4f+R3r)/(R4f−R3r)<1.6  (2),0.25<(R4f+R3r)/(R4f−R3r)<1.3  (2-1),−0.5<f1/f3<1  (3),−0.4<f1/f3<0.3  (3-1),−0.5<(R3f−R3r)/(R3f+R3r)<0.3  (4),−0.4<(R3f−R3r)/(R3f+R3r)<0.15  (4-1),0.5<f·tan ω/R5r<10  (5),0.7<f·tan ω/R5r<3  (5-1),−2<f/f5<−0.2  (6),−1.5<f/f5<−0.4  (6-1),0.8<f/f1<2.5  (7),1<f/f1<2  (7-1), and−0.8<f/f3<0.3  (8), where

-   -   f is a focal length of a whole system,    -   f1 is a focal length of the first lens,    -   f3 is a focal length of the third lens,    -   f5 is a focal length of the fifth lens,    -   f345 is a composite focal length of the third to fifth lenses,    -   ω is a half angle of view,    -   R3r is a paraxial radius of curvature of an image side surface        of the third lens,    -   R3f is a paraxial radius of curvature of an object side surface        of the third lens,    -   R4f is a paraxial radius of curvature of the object side surface        of the fourth lens, and    -   R5r is a paraxial radius of curvature of the image side surface        of the fifth lens.

The imaging apparatus of the present invention includes the imaging lensof the present invention.

According to the imaging lens of the present invention, in the imaginglens which is composed of five lenses as a whole, a configuration ofeach lens element is optimized, and particularly the shapes of the firstand fifth lenses are appropriately formed. Therefore, it is possible toachieve a lens system that has high resolution performance in the rangefrom the central angle of view to the peripheral angle of view whiledecreasing the total length thereof.

Further, according to the imaging apparatus of the present invention,imaging signals based on an optical image formed by the imaging lens ofthe present invention, which has high imaging performance, are output.Therefore, it is possible to obtain a photographed image with highresolution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lens cross-sectional view illustrating a first configurationexample of an imaging lens according to an embodiment of the presentinvention and corresponding to Example 1;

FIG. 2 is a lens cross-sectional view illustrating a secondconfiguration example of an imaging lens according to an embodiment ofthe present invention and corresponding to Example 2;

FIG. 3 is a lens cross-sectional view illustrating a third configurationexample of an imaging lens according to an embodiment of the presentinvention and corresponding to Example 3;

FIG. 4 is a lens cross-sectional view illustrating a fourthconfiguration example of an imaging lens according to an embodiment ofthe present invention and corresponding to Example 4;

FIG. 5 is a lens cross-sectional view illustrating a fifth configurationexample of an imaging lens according to an embodiment of the presentinvention and corresponding to Example 5;

FIG. 6 is a lens cross-sectional view illustrating a sixth configurationexample of an imaging lens according to an embodiment of the presentinvention and corresponding to Example 6;

FIG. 7 is a ray diagram of the imaging lens shown in FIG. 1;

FIG. 8 is an aberration diagram illustrating various aberrations of animaging lens according to Example 1 of the present invention, whereSection A shows a spherical aberration, Section B shows astigmatism(curvature of field), Section C shows distortion, and Section D shows alateral chromatic aberration;

FIG. 9 is an aberration diagram illustrating various aberrations of animaging lens according to Example 2 of the present invention, whereSection A shows a spherical aberration, Section B shows astigmatism(curvature of field), Section C shows distortion, and Section D shows alateral chromatic aberration;

FIG. 10 is an aberration diagram illustrating various aberrations of animaging lens according to Example 3 of the present invention, whereSection A shows a spherical aberration, Section B shows astigmatism(curvature of field), Section C shows distortion, and Section D shows alateral chromatic aberration;

FIG. 11 is an aberration diagram illustrating various aberrations of animaging lens according to Example 4 of the present invention, whereSection A shows a spherical aberration, Section B shows astigmatism(curvature of field), Section C shows distortion, and Section D shows alateral chromatic aberration;

FIG. 12 is an aberration diagram illustrating various aberrations of animaging lens according to Example 5 of the present invention, whereSection A shows a spherical aberration, Section B shows astigmatism(curvature of field), Section C shows distortion, and Section D shows alateral chromatic aberration;

FIG. 13 is an aberration diagram illustrating various aberrations of animaging lens according to Example 6 of the present invention, whereSection A shows a spherical aberration, Section B shows astigmatism(curvature of field), Section C shows distortion, and Section D shows alateral chromatic aberration;

FIG. 14 is a diagram illustrating an imaging apparatus which is acellular phone terminal including the imaging lens according to thepresent invention; and

FIG. 15 is a diagram illustrating an imaging apparatus which is asmartphone including the imaging lens according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings.

FIG. 1 shows a first configuration example of an imaging lens accordingto a first embodiment of the present invention. The configurationexample corresponds to a lens configuration of a first numerical valueexample (Table 1 and Table 2) to be described later. Likewise, FIGS. 2to 6 show cross sections of second to sixth configuration examplescorresponding to the imaging lenses according to second to sixthembodiments to be described later. The second to sixth configurationexamples correspond to lens configurations of the second to sixthnumerical value examples (Tables 3 to 12) to be described later. InFIGS. 1 to 6, the reference sign Ri represents a radius of curvature ofi-th surface, where the number is the sequential number thatsequentially increases as it gets closer to an image side (an imagingside) when a surface of a lens element closest to an object side isregarded as a first surface. The reference sign Di represents an on-axissurface spacing between i-th surface and (i+1)th surface on an opticalaxis Z1. Since the respective configuration examples are basicallysimilar in configuration, the following description will be given on thebasis of the first configuration example of the imaging lens shown inFIG. 1, and the configuration examples shown in FIGS. 2 to 6 will bealso described as necessary. Further, FIG. 7 is an optical path diagramof the imaging lens L shown in FIG. 1, and shows an optical path of rays2 on the optical axis from an object point at the infinite distance andan optical path of rays 3 at the maximum angle of view.

An imaging lens L according to an embodiment of the present invention isappropriate to be used in various kinds of imaging apparatuses usingimaging devices such as a CCD and a CMOS. Especially, the imaging lens Lis appropriate to be used in relatively small-sized mobile terminalapparatus, for example, such as a digital still camera, a cellular phonewith a camera, a smartphone, a tablet terminal, and a PDA. This imaginglens L includes, along the optical axis Z1, a first lens L1, a secondlens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 in thisorder from the object side.

FIG. 14 is a schematic diagram illustrating a cellular phone terminal,which is an imaging apparatus 1 according to an embodiment of thepresent invention. The imaging apparatus 1 according to the embodimentof the present invention includes imaging lens L according to thepresent embodiment and an imaging device 100 (refer to FIG. 1), such asa COD, which outputs imaging signals based on an optical image formed bythe imaging lens L. The imaging device 100 is disposed at an imageformation surface (image plane R14) of the imaging lens L.

FIG. 15 is a schematic diagram illustrating a smartphone which is animaging apparatus 501 according to an embodiment of the presentinvention. The imaging apparatus 501 according to the embodiment of thepresent invention includes a camera unit 541 including the imaging lensL according to the present embodiment and the imaging device 100 (referto FIG. 1), such as a CCD, which outputs imaging signals based on anoptical image formed by the imaging lens L. The imaging device 100 isdisposed at the image formation surface (image plane R14) of the imaginglens L.

Various optical members CG may be disposed between the fifth lens L5 andthe imaging device 100 based on the configuration of a camera on whichthe imaging lens is mounted. For example, a flat-plate-shaped opticalmember, such as a cover glass for protecting an imaging surface and aninfrared-ray cut filter, may be disposed. In this case, for example, aflat-plate-shaped cover glass to which a coating having an effect of afilter, such as an infrared-ray cut filter and an ND filter, has beenapplied, or a material having the same effect may be used as the opticalmember CG.

Alternatively, an effect similar to the optical member CG may be givento the fifth lens L5 or the like by applying a coating to the fifth lensL5 or the like without using the optical member CG. Thereby, it ispossible to reduce the number of components, and to reduce the totallength.

Further, it is desirable that the imaging lens L includes an aperturestop St disposed on the object side of an object side surface of thesecond lens L2. Since the aperture stop St is disposed on the objectside of the object side surface of the second lens L2 in such a manner,especially in a peripheral portion of an imaging area, it is possible toprevent an angle of incidence of rays, which pass through the opticalsystem and are incident onto an imaging surface (imaging device), frombecoming large. In order to further enhance this effect, it is moredesirable that the aperture stop St be disposed on the object side of anobject side surface of the first lens L1. Here, the expression “disposedon the object side of the object side surface of the second lens L2”means that the position of the aperture stop in the optical axisdirection is the same as an intersection point between an on-axismarginal ray and the object side surface of the second lens L2 orlocated on the object side of the intersection point. Likewise, theexpression “disposed on the object side of an object side surface of thefirst lens L1” means that the position of the aperture stop in theoptical axis direction is the same as an intersection point between anon-axis marginal ray and the object side surface of the first lens L1 orlocated on the object side of the intersection point. In the embodimentsof the present invention, the imaging lenses of the first to sixthconfiguration examples (refer to FIGS. 1 to 6) are configurationexamples in which the aperture stop St is disposed on the object side ofthe object side surface of the first lens L1. It should be noted thatthe aperture stop St shown herein does not necessarily represent thesize or shape thereof but shows the position thereof on the optical axisZ1.

Furthermore, when the aperture stop St is disposed on the object side ofthe object side surface of the first lens L1 in the optical axis, it isdesirable that the aperture stop St be disposed on the image side of avertex of the surface of the first lens L1. When the aperture stop St isdisposed on the image side of the vertex of the surface of the firstlens L1 in such a manner, it is possible to reduce the total length ofthe imaging lens including the aperture stop St. In the first to sixthembodiments, the aperture stop St is disposed on the image side of thevertex of the surface of the first lens L1. However, the invention isnot limited to the embodiments, and the aperture stop St may be disposedon the object side of the vertex of the surface of the first lens L1.The arrangement, in which the aperture stop St is disposed on the objectside of the vertex of the surface of the first lens L1, is slightlydisadvantageous in terms of securing a peripheral light amount, comparedwith a case where the aperture stop St is disposed on the image side ofthe vertex of the surface of the first lens L1. However, the arrangementcan prevent an angle of incidence of rays, which pass through theoptical system and are incident onto the imaging surface (imagingdevice), from becoming large in the peripheral portion of the imagingarea in a more desirable manner.

In the imaging lens L, the first lens L1 has a positive refractive powerin the vicinity of the optical axis, and has a meniscus shape which isconvex toward the object side in the vicinity of the optical axis. Asshown in the embodiments, by making the first lens L1, which is a lensclosest to the object, have a positive refractive power and have ameniscus shape which is convex toward the object side in the vicinity ofthe optical axis, the position of the rear side principal point of thefirst lens L1 can be set to be close to the object, and thus it ispossible to appropriately reduce the total length.

The second lens L2 has a negative refractive power in the vicinity ofthe optical axis. As in the first embodiment shown in FIG. 1, the secondlens L2 has a meniscus shape which is concave toward the object side inthe vicinity of the optical axis. Hence, it is possible to suppressoccurrence of astigmatism while satisfactorily correcting a chromaticaberration.

The third lens L3 has a meniscus shape which is convex toward the imageside in the vicinity of the optical axis. Thereby, it is possible toappropriately suppress occurrence of astigmatism. As long as the thirdlens L3 has a meniscus shape which is convex toward the image side inthe vicinity of the optical axis, it is possible to adopt aconfiguration in which the third lens L3 has a positive refractive powerin the vicinity of the optical axis, and it is also possible to adopt aconfiguration in which the third lens L3 has a negative refractive powerin the vicinity of the optical axis. When the third lens L3 isconfigured to have a positive refractive power in the vicinity of theoptical axis, it is possible to more appropriately reduce the totallength. When the third lens L3 is configured to have a negativerefractive power in the vicinity of the optical axis, it is possible tomore satisfactorily correct a spherical aberration. The first, second,and fifth embodiments are configuration examples in which the third lensL3 is configured to have a positive refractive power in the vicinity ofthe optical axis. The third, fourth, and sixth embodiments areconfiguration examples in which the third lens L3 is configured to havea negative refractive power in the vicinity of the optical axis.

The fourth lens L4 has a positive refractive power in the vicinity ofthe optical axis. Thereby, especially at the medium angle of view, it ispossible to prevent the angle of incidence of rays, which pass throughthe optical system and are incident onto the image formation surface(imaging device), from becoming large. The fourth lens L4 has a positiverefractive power, and is convex toward the object side in the vicinityof the optical axis. Hence, it is possible to satisfactorily correct aspherical aberration, while appropriately reducing the total length. Asin the first embodiment shown in FIG. 1, it is desirable that the fourthlens L4 has a biconvex shape in the vicinity of the optical axis. Inthis case, it is possible to satisfactorily correct a sphericalaberration.

The fifth lens L5 has a negative refractive power in the vicinity of theoptical axis. A lens, which has a negative refractive power in thevicinity of the optical axis, is disposed to be closest to the imageside of the imaging lens, and the imaging lens is configured, as awhole, to include, in order from the object side, a lens group having apositive refractive power and a lens group having a negative refractivepower. Thereby, it is possible to appropriately reduce the total length.The fifth lens L5 has a negative refractive power in the vicinity of theoptical axis, whereby it is possible to appropriately correct acurvature of field. When the fifth lens L5 is concave toward the imageside in the vicinity of the optical axis, it is possible to moreappropriately reduce the total length. In order to further enhance thiseffect, as shown in the first embodiment, it is desirable that the fifthlens L5 have a meniscus shape which is concave toward the image side inthe vicinity of the optical axis.

The fifth lens L5 has at least one inflection point within an effectivediameter of the image side surface. The “inflection point” on the imageside surface of the fifth lens L5 is defined as a point at which theshape of the image side surface of the fifth lens L5 changes from aconvex shape to a concave shape (or from a concave shape to a convexshape) toward the image side. The inflection point can be disposed at anarbitrary position on the outside in a radial direction from the opticalaxis as long as the point is within the effective diameter of the imageside surface of the fifth lens L5. As shown in the first embodiment, byforming the image side surface of the fifth lens L5 in a shape in whichthe image side surface has at least one inflection point, especially ina peripheral portion of an image formation area, it is possible toprevent the angle of incidence of rays, which pass through the opticalsystem and are incident onto the image formation surface (imagingdevice), from becoming large.

According to the imaging lens L, in the imaging lens which is composedof five lenses as a whole, a configuration of each lens element of thefirst to fifth lenses L1 to L5 is optimized. Therefore, it is possibleto achieve a lens system that has high resolution performance whiledecreasing the total length thereof.

In the imaging lens L, in order to enhance the performance thereof, itis desirable that at least one surface of each lens of the first tofifth lenses L1 to L5 be formed as an aspheric surface.

Further, it is desirable that each of the lenses L1 to L5 constitutingthe imaging lens L be not formed as a cemented lens but a single lens.The reason is that, compared with a case where any of the lenses L1 toL5 is formed as a cemented lens, since the number of aspheric surfacesincreases, a degree of freedom in design of each lens is enhanced, andit is possible to appropriately achieve reduction in the total lengththereof.

Further, for example, as in the imaging lenses according to the first tosixth embodiments, when each lens configuration of the first to fifthlenses L1 to L5 of the imaging lens L is set such that the total angleof view is equal to or greater than 60 degrees, the imaging lens L canbe appropriately applied to a cellular phone terminal and the like whichare often used in a close-up shot.

Next, effects and advantages of the conditional expressions of theimaging lens L configured as described above will be described indetail. Regarding the following conditional expressions, it is desirablethat the imaging lens L satisfies anyone or an arbitrary combination ofthe conditional expressions. It is desirable that the conditionalexpressions to be satisfied be appropriately selected in accordance withfactors necessary for the imaging lens L.

First, it is desirable that the composite focal length f345 of the thirdto fifth lenses L3 to L5 and the focal length f of the whole systemsatisfy the following conditional expression (1).−2<f/f345<−0.25  (1)

The conditional expression (1) defines a desirable numerical range of aratio of the focal length f of the whole system to the composite focallength f345 of the third to fifth lenses L3 to L5. By maintaining thecomposite focal length f345 of the third to fifth lenses L3 to L5 suchthat f/f345 is greater than the lower limit of the conditionalexpression (1), the negative refractive power of the lens group composedof the third to fifth lenses L3 to L5 does not become excessively strongrelative to the refractive power of the whole system, and thus,especially at the medium angle of view, it is possible to prevent theangle of incidence of rays, which pass through the optical system andare incident onto the image formation surface (imaging device), frombecoming large. By securing the composite focal length f345 of the thirdto fifth lenses L3 to L5 such that f/f345 is less than the upper limitof the conditional expression (1), the refractive power of the lensgroup composed of the third to fifth lenses L3 to L5 does not becomeexcessively weak relative to the refractive power of the whole system,and thus it is possible to appropriately reduce the total length. Inorder to further enhance this effect, it is desirable to satisfy theconditional expression (1-1), and it is more desirable to satisfy theconditional expression (1-2).−1.8<f/f345<−0.3  (1-1)−1.6<f/f345<−0.4  (1-2)

Further, it is desirable that the paraxial radius of curvature R4f ofthe object side surface of the fourth lens L4 and the paraxial radius ofcurvature R3r of the image side surface of the third lens L3 satisfy thefollowing conditional expression (2).0.2<(R4f+R3r)/(R4f−R3r)<1.6  (2)

The conditional expression (2) defines each of a desirable numericalrange of the paraxial radius of curvature R4f of the object side surfaceof the fourth lens L4 and a desirable numerical range of the paraxialradius of curvature R3r of the image side surface of the third lens L3.By setting the paraxial radius of curvature R4f of the object sidesurface of the fourth lens L4 and the paraxial radius of curvature R3rof the image side surface of the third lens L3 such that(R4f+R3r)/(R4f−R3r) is greater than the lower limit of the conditionalexpression (2), it is possible to satisfactorily correct astigmatism. Bysetting the paraxial radius of curvature R4f of the object side surfaceof the fourth lens L4 and the paraxial radius of curvature R3r of theimage side surface of the third lens L3 such that (R4f+R3r)/(R4f−R3r) isless than the upper limit of the conditional expression (2), it ispossible to satisfactorily correct a spherical aberration. In order tofurther enhance this effect, it is more desirable to satisfy thefollowing conditional expression (2-1), and it is even more desirable tosatisfy the conditional expression (2-2).0.25<(R4f+R3r)/(R4f−R3r)<1.3  (2-1)0.3<(R4f+R3r)/(R4f−R3r)<1.2  (2-2)

It is desirable that the focal length f3 of the third lens L3 and thefocal length f1 of the first lens L1 satisfy the following conditionalexpression (3).−0.5<f1/f3<1  (3)

The conditional expression (3) defines a desirable numerical range of aratio of the focal length f1 of the first lens L1 to the focal length f3of the third lens L3. When the third lens L3 has a negative refractivepower, by securing the refractive power of the third lens L3 relative tothe refractive power of the first lens L1 such that f1/f3 is greaterthan the lower limit of the conditional expression (3), the negativerefractive power of the third lens L3 does not become excessively strongrelative to the refractive power of the first lens L1. As a result, itis possible to appropriately reduce the total length. When the thirdlens L3 has a positive refractive power, by securing the refractivepower of the third lens L3 relative to the refractive power of the firstlens L1 such that f1/f3 is less than the upper limit of the conditionalexpression (3), the positive refractive power of the third lens L3 doesnot become excessively strong relative to the refractive power of thefirst lens L1. As a result, it is possible to satisfactorily correct aspherical aberration. In order to further enhance this effect, it isdesirable to satisfy the conditional expression (3-1), and it is moredesirable to satisfy the conditional expression (3-2).−0.4<f1/f3<0.3  (3-1)−0.35<f1/f3<0.1  (3-2)

It is desirable that the paraxial radius of curvature R3f of the objectside surface of the third lens L3 and the paraxial radius of curvatureR3r of the image side surface of the third lens L3 satisfy the followingconditional expression (4).−0.5<(R3f−R3r)/(R3f+R3r)<0.3  (4)

The conditional expression (4) defines each of a desirable numericalrange of the paraxial radius of curvature R3f of the object side surfaceof the third lens L3 and a desirable numerical range of the paraxialradius of curvature R3r of the image side surface of the third lens L3.By setting the paraxial radius of curvature R3f of the object sidesurface of the third lens L3 and the paraxial radius of curvature R3r ofthe image side surface of the third lens L3 such that(R3f−R3r)/(R3f+R3r) is greater than the lower limit of the conditionalexpression (4), it is possible to appropriately reduce the total length.By setting the paraxial radius of curvature R3f of the object sidesurface of the third lens L3 and the paraxial radius of curvature R3r ofthe image side surface of the third lens L3 such that(R3f−R3r)/(R3f+R3r) is less than the upper limit of the conditionalexpression (4), it is possible to satisfactorily correct a sphericalaberration. In order to further enhance this effect, it is moredesirable to satisfy the following conditional expression (4-1).−0.4<(R3f−R3r)/(R3f+R3r)<0.15  (4-1)

Further, it is desirable that the focal length f of the whole system,the half angle of view ω, and the paraxial radius of curvature R5r ofthe image side surface of the fifth lens L5 satisfy the followingconditional expression (5).0.5<f·ω/R5r<10  (5)

The conditional expression (5) defines a desirable numerical range of aratio of the paraxial image height (f·tan ω) to the paraxial radius ofcurvature R5r of the image side surface of the fifth lens L5. By settingthe paraxial image height (f·tan ω) relative to the paraxial radius ofcurvature R5r of the image side surface of the fifth lens L5 such thatf·tan ω/R5r is greater than the lower limit of the conditionalexpression (5), an absolute value of the paraxial radius of curvatureR5r of the image side surface of the fifth lens L5, which is a surfaceof the imaging lens closest to the image side, does not becomeexcessively large relative to the paraxial image height (f·tan ω), andthus, it is possible to sufficiently correct a curvature of field whilereducing the total length. Further, by setting the paraxial image height(f·tan ω) relative to the paraxial radius of curvature R5r of the imageside surface of the fifth lens L5 such that f·tan ω/R5r is less than theupper limit of the conditional expression (5), the absolute value of theparaxial radius of curvature R5r of the image side surface of the fifthlens L5, which is a surface of the imaging lens closest to the imageside, does not become excessively small relative to the paraxial imageheight (f·tan ω), and thus, especially at the medium angle of view, itis possible to prevent the angle of incidence of rays, which passthrough the optical system and are incident onto the image formationsurface (imaging device), from becoming large. In order to furtherenhance this effect, it is desirable to satisfy the conditionalexpression (5-1).0.7<f·tan ω/R5r<3  (5-1)

Further, it is desirable that the focal length f5 of the fifth lens L5and the focal length f of the whole system satisfy the followingconditional expression (6).−2<f/f5<−0.2  (6)

The conditional expression (6) defines a desirable numerical range of aratio of the focal length f of the whole system to the focal length f5of the fifth lens L5. By maintaining the refractive power of the fifthlens L5 such that f/f5 is greater than the lower limit of theconditional expression (6), the refractive power of the fifth lens L5does not become excessively strong relative to the positive refractivepower of the whole system, and thus, especially at the medium angle ofview, it is possible to prevent the angle of incidence of rays, whichpass through the optical system and are incident onto the imageformation surface (imaging device), from becoming large. By securing therefractive power of the fifth lens L5 such that f/f5 is less than theupper limit of the conditional expression (6), the refractive power ofthe fifth lens L5 does not become excessively weak relative to therefractive power of the whole system, and thus it is possible toappropriately reduce the total length while satisfactorily correcting acurvature of field. In order to further enhance this effect, it is moredesirable to satisfy the conditional expression (6-1).−1.5<f/f5<−0.4  (6-1)

Further, it is desirable that the focal length f1 of the first lens L1and the focal length f of the whole system satisfy the followingconditional expression (7).0.8<f/f1<2.5  (7)

The conditional expression (7) defines a desirable numerical range of aratio of the focal length f of the whole system to the focal length f1of the first lens L1. By securing the refractive power of the first lensL1 such that f/f1 is greater than the lower limit of the conditionalexpression (7), the positive refractive power of the first lens L1 doesnot become excessively weak relative to the refractive power of thewhole system, and thus it is possible to appropriately reduce the totallength. By maintaining the refractive power of the first lens L1 suchthat f/f1 is less than the upper limit of the conditional expression(7), the positive refractive power of the first lens L1 does not becomeexcessively strong relative to the refractive power of the whole system,and thus it is possible to satisfactorily correct especially a sphericalaberration. In order to further enhance this effect, it is moredesirable to satisfy the conditional expression (7-1).1<f/f1<2  (7-1)

Further, the focal length f3 of the third lens L3 and the focal length fof the whole system satisfy the following conditional expression (8).−0.8<f/f3<0.3  (8)

The conditional expression (8) defines a desirable numerical range of aratio of the focal length f of the whole system to the focal length f3of the third lens L3. When the third lens L3 has a negative refractivepower, by maintaining the refractive power of the third lens L3 suchthat f/f3 is greater than the lower limit of the conditional expression(8), the negative refractive power of the third lens L3 does not becomeexcessively strong relative to the refractive power of the whole system,and thus it is possible to appropriately reduce the total length. Whenthe third lens L3 has a positive refractive power, by securing therefractive power of the third lens L3 such that f/f3 is less than theupper limit of the conditional expression (8), the positive refractivepower of the third lens L3 does not become excessively strong relativeto the refractive power of the whole system, and thus it is possible tosatisfactorily correct a spherical aberration. In order to furtherenhance this effect, it is more desirable to satisfy the conditionalexpression (8-1).−0.65<f/f3<0.1  (8-1)

Next, referring to FIGS. 2 to 6 imaging lenses according to second tosixth embodiments of the present invention will be described in detail.In the imaging lenses according to the first to sixth embodiments shownin FIGS. 1 to 6, all surfaces of the first to fifth lenses L1 to L5 areformed to be aspheric. As in the first embodiment, the imaging lensesaccording to the second to sixth embodiments of the present inventionsubstantially consist of, in order from the object side, five lenses of:the first lens L1 that has a positive refractive power and has ameniscus shape which is convex toward the object side; the second lensL2 that has a negative refractive power and has a meniscus shape whichis concave toward the object side; the third lens L3 that has a meniscusshape which is convex toward the image side; the fourth lens L4 that hasa positive refractive power and is convex toward the object side; andthe fifth lens L5 that has a negative refractive power and has at leastone inflection point on an image side surface. Hence, in the followingfirst to sixth embodiments, only the different specific configurationsof the lenses constituting the respective lens groups will be described.Since the configurations which are common among the first to sixthembodiments respectively have the same effects, configurations andeffects thereof will be described in order of the sequence numbers ofthe embodiments, and the configurations and effects common to the otherembodiments will not be repeatedly described but will be omitted.

As in the second embodiment shown in FIG. 2, the fourth lens L4 may havea meniscus shape which is convex toward the object side in the vicinityof the optical axis. When the fourth lens L4 has a meniscus shape whichis convex toward the object side in the vicinity of the optical axis,the position of the rear side principal point of the fourth lens L4 canbe set to be close to the object side, and thus it is possible toappropriately reduce the total length. Further, in the secondembodiment, the configurations of the first to third lenses L1 to L3 andthe fifth lens L5 are common to the first embodiment. According to therespective lens configurations, it is possible to obtain the sameeffects as the respective corresponding configurations of the firstembodiment.

As in the third embodiment shown in FIG. 3, the third lens L3 may beconfigured to have a negative refractive power in the vicinity of theoptical axis. In this case, it is possible to satisfactorily correct aspherical aberration. In the third embodiment, the lens configurationsof the first lens L1, the second lens L2, the fourth lens L4 and thefifth lens L5 are common to the first embodiment. According to therespective lens configurations, it is possible to obtain the sameeffects as the respective corresponding configurations of the firstembodiment.

As in the fourth embodiment shown in FIG. 4, the third lens L3 may bemade to have a negative refractive power in the vicinity of the opticalaxis in the same manner as the third embodiment, the fifth lens L5 maybe made to have a biconcave shape in the vicinity of the optical axis,and the first lens L1, the second lens L2, and the fourth lens L4 mayhave the same lens configurations as the first embodiment. By making thethird lens L3 have the negative refractive power in the vicinity of theoptical axis, it is possible to satisfactorily correct a sphericalaberration and a chromatic aberration. Further, by making the fifth lensL5 have a biconcave shape in the vicinity of the optical axis, it iseasy to make the fifth lens L5, which is disposed to be closest to theimage side of the imaging lens L, have a sufficiently strong negativerefractive power, and it is possible to more appropriately reduce thetotal length. In the fourth embodiment, the lens configurations of thefirst lens L1, the second lens L2, and the fourth lens L4 are common tothe first embodiment. According to the respective lens configurations,it is possible to obtain the same effects as the respectivecorresponding configurations of the first embodiment.

In the imaging lens L according to the fifth embodiment shown in FIG. 5,the lens configurations of the first to fifth lenses L1 to L5 are commonto the first embodiment. Therefore, according to the respective lensconfigurations, it is possible to obtain the same effects as therespective corresponding configurations of the first embodiment.

In the imaging lens L according to the sixth embodiment shown in FIG. 6,the lens configurations of the first to fifth lenses L1 to L5 are commonto the third embodiment. Therefore, according to the respective lensconfigurations, it is possible to obtain the same effects as therespective corresponding configurations of the third embodiment.

As described above, according to the imaging lens of the embodiment ofthe present invention, in the imaging lens which is composed of fivelenses as a whole, the configuration of each lens element is optimized.Therefore, it is possible to achieve a lens system that has highresolution performance while decreasing the total length thereof.

By satisfying appropriately desirable conditions, it is possible toachieve higher imaging performance. Furthermore, according to theimaging apparatus of the embodiment, imaging signals based on an opticalimage, which is formed by the high-performance imaging lens according tothe embodiment, are output. Therefore, it is possible to obtain aphotographed image with high resolution in the range from the centralangle of view to the peripheral angle of view.

Next, specific numerical examples of the imaging lens according to theembodiment of the present invention will be described. Hereinafter, aplurality of numerical examples will be described collectively.

Table 1 and Table 2, which will be given later, show specific lens datacorresponding to the configuration of the imaging lens shown in FIG. 1.Specifically, Table 1 shows basic lens data, and Table 2 shows data onaspheric surfaces. In the lens data shown in Table 1, the column ofsurface number Si shows the surface number of the i-th surface in theimaging lens of Example 1. The surface of the lens element closest tothe object side is the first surface (the aperture stop St is thefirst), and surface numbers sequentially increase toward the image side.The column of the radius of curvature Ri shows values (mm) of the radiusof curvature of i-th surface from the object side to correspond to thereference sign Ri in FIG. 1. Likewise, the column of the on-axis surfacespacing Di shows spaces (mm) on the optical axis between the i-thsurface Si and the (i+1)th surface Si+1 on the optical axis from theobject side. The column of Ndj shows values of the refractive index ofthe j-th optical element from the object side for the d-line (587.56nm). The column of νdj shows values of the Abbe number of the j-thoptical element from the object side for the d-line. It should be notedthat, in each piece of lens data, as various data items, values of thefocal length f of the whole system (mm), the back focal length Bf (mm),and the total lens length TL (mm) are respectively shown. In addition,the back focal length Bf indicates an air-converted value, and likewise,in the total lens length TL, the back focal length portion uses anair-converted value.

In the imaging lens according to Example 1, both surfaces of each of thefirst to fifth lenses L1 to L5 are aspheric. In the basic lens datashown in Table 1, the radii of curvature of these aspheric surfaces arerepresented as numerical values of the radius of curvature near theoptical axis (paraxial radius of curvature).

Table 2 shows aspheric surface data in the imaging lens system accordingto Example 1. In the numerical values represented as the asphericsurface data, the reference sign “E” means that a numerical valuefollowing this is a “exponent” having a base of 10 and that thisnumerical value having a base of 10 and expressed by an exponentialfunction is multiplied by a numerical value before the “E”. For example,this means that “1.0E-02” is “1.0×10⁻²”.

As aspheric surface data, values of coefficients Ai and KA in theaspheric surface expression represented by the following expression (A)are shown. Specifically, Z represents the length (mm) of a perpendicularfrom a point on an aspheric surface at height h from an optical axis toa plane that contacts with the vertex of the aspheric surface (the planeperpendicular to the optical axis).Z=C·h ²/{1(1−KA·C ² ·h ²)^(1/2) }+ΣAi·h ^(i)  (A)

Here,

-   -   Z is a depth of the aspheric surface (mm),    -   h is a distance (height) from the optical axis to the lens        surface (mm),    -   C is a paraxial curvature=1/R    -   (R: a paraxial radius of curvature),    -   Ai is an i-th order aspheric surface coefficient (i is an        integer equal to or greater than 3), and    -   KA is an aspheric surface coefficient.

As in the imaging lens according to the above-mentioned Example 1,Tables 3 to 12 show specific lens data as Examples 2 to 6, correspondingto the configuration of the imaging lenses shown in FIGS. 2 to 6. In theimaging lenses according to Examples 1 to 6, both surfaces of each ofthe first to fifth lenses L1 to L5 are aspheric.

FIG. 8, Section A to Section D show a spherical aberration, astigmatism(curvature of field), distortion (a distortion aberration), and alateral chromatic aberration (a chromatic aberration of magnification)in the imaging lens of Example 1, respectively. Each aberration diagramillustrating a spherical aberration, astigmatism (curvature of field),and distortion (a distortion aberration) shows an aberration for thed-line (a wavelength of 587.56 nm) as a reference wavelength. Thediagram of a spherical aberration diagram and the diagram of a lateralchromatic aberration diagram show also aberrations for the F-line (awavelength of 486.1 nm) and the C-line (a wavelength of 656.27 nm). Thediagram of a spherical aberration also shows an aberration for theg-line (a wavelength of 435.83 nm). In the diagram of astigmatism, thesolid line indicates an aberration in the sagittal direction (S), andthe broken line indicates an aberration in the tangential direction (T).Fno. indicates an F-number, and ω indicates a half angle of view.

Likewise, FIG. 9, Section A to D to FIG. 13, Section A to D show variousaberrations of the imaging lenses of Examples 2 to 6.

Table 13 collectively shows values of the conditional expressions (1)and (8) of Examples 1 to 6 according to the present invention.

As can be seen from the above-mentioned numerical value data andaberration diagrams, in each example, high imaging performance isachieved while the total length is reduced.

The imaging lens of the present invention is not limited to theabove-mentioned embodiments and examples, and may be modified to variousforms. For example, the values of the radius of curvature, the on-axissurface spacing, the refractive index, the Abbe number, the asphericsurface coefficient, and the like of the lens elements are not limitedto the values shown in the numerical examples, and may have differentvalues.

Further, in the description of each of all the examples, it is a premisethat the imaging lens is used with fixed focus, but it may be possibleto adopt a configuration in which focus is adjustable. For example, theimaging lens may be configured in such a manner that autofocusing ispossible by extending the whole lens system or by moving some lenses onthe optical axis.

TABLE 1 EXAMPLE 1 f = 4.367, Bf = 1.020, TL = 5.038 Si Ri Di Ndj νdj1(APERTURE ∞ −0.182 STOP) *2 1.58994 0.412 1.53390 55.95 *3 10.916770.100 *4 −7.55071 0.349 1.63320 22.00 *5 −20.94753 0.600 *6 −4.163940.493 1.53380 55.80 *7 −4.18360 0.506 *8 20.94741 0.441 1.63370 23.70 *9−20.94753 0.100 *10  9.56013 1.017 1.53380 55.80 *11  2.07517 0.487 12 ∞0.210 1.51633 64.14 13 ∞ 0.394 14 ∞ *ASPHERIC SURFACE

TABLE 2 EXAMPLE 1 • ASPHERIC SURFACE DATA SURFACE NUMBER KA A3 A4 A5 A62 −2.0197553E+01 −2.9510637E−02 9.6611570E−01 −1.5730920E+001.1943657E+00 3 −2.3479016E+01 −3.0225634E−02 2.0961256E−01−1.2891727E+00 2.5969819E+00 4 −1.6806296E+01 −3.9039137E−021.9213540E−01 −1.3508412E+00 8.0616469E+00 5 1.0000090E+00 4.3782479E−02−3.8164370E−02 −1.7068379E+00 1.1503519E+01 6 −2.4852523E+01−1.2182741E−02 −4.6425680E−03 −5.5318142E−01 −2.7144082E−01 7−9.8533211E+00 1.8157541E−02 −3.2361114E−01 3.7057001E−01 −2.3488763E−018 9.9930846E−01 1.3756403E−01 −6.7018041E−01 2.4025932E+00−5.9726073E+00 9 1.7198259E+00 2.3336216E−01 4.4292280E−02−4.3842794E−01 3.1625362E−01 10  −6.2360277E+00 3.3852163E−01−3.1788433E−01 −3.0644189E−01 3.1012273E−01 11  −4.4784535E+001.4057931E−01 −4.3922311E−01 6.9456892E−01 −8.6625712E−01 A7 A8 A9 A10A11 2 −1.7893743E+00 6.8236503E+00 −1.0866183E+01 −6.8436225E+004.7030947E+01 3 −1.3282881E+00 −2.7816247E+00 3.6666605E+005.0524651E+00 −3.7898934E+01 4 −3.9675754E+01 1.2593862E+02−2.3505639E+02 2.2945706E+02 −5.2572069E+01 5 −3.2342947E+014.1416439E+01 −1.5381973E+00 −5.2528365E+01 1.1835389E+01 64.7866473E+00 −7.9996572E+00 −8.2976059E−01 1.3508711E+01 −8.0753650E+007 −4.5179747E−01 5.4069540E−01 5.7289226E−01 −8.1807402E−01−2.8775394E−01 8 1.0038132E+01 −1.3063663E+01 1.3778315E+01−1.2254160E+01 9.4197398E+00 9 −4.7434984E−01 7.7608183E−01−5.2820940E−01 1.0297370E−01 5.5041402E−02 10  3.8099209E−02−8.5542504E−02 −1.2920455E−02 2.2928336E−02 5.8175333E−03 11 6.9186540E−01 −3.1208015E−01 6.9672117E−02 −4.3303095E−03 −3.1620810E−03A12 A13 A14 A15 A16 2 −4.9548162E+01 −2.2531192E+01 7.7139454E+01−3.0912496E+01 −3.8820784E+01 3 8.7522021E+01 −6.6543414E+01−3.9322545E+01 6.0173274E+01 3.2259029E+01 4 −8.4509909E+01−2.6080272E+01 2.4956388E+02 −3.2385285E+02 2.1680301E+02 51.1237551E+02 −1.3474351E+02 −6.0459613E+00 1.2367767E+02 −9.8766846E+016 −5.8106217E+00 3.9388932E+00 1.7658702E+00 4.1933337E+00−8.8144865E+00 7 7.6972584E−01 −3.3121303E−01 −6.6778308E−021.4422193E−01 −4.8070072E−02 8 −5.4699064E+00 1.6346800E+007.3836421E−02 1.6029368E−02 −2.4072519E−01 9 −4.7113672E−021.3827338E−02 2.0858623E−03 −5.4618365E−04 −1.6509934E−03 10 −7.7556085E−03 1.0922126E−04 1.0757796E−03 −3.7161170E−05 −1.5545326E−0411  2.8880576E−03 −9.6968859E−04 6.7008595E−05 −4.0741827E−054.4484475E−05 A17 A16 2 4.2468422E+01 −1.2671572E+01 3 −6.3117794E+012.0574300E+01 4 −7.8600554E+01 1.1683190E+01 5 2.8344015E+01−1.3900572E+00 6 5.0853395E+00 −1.0502146E+00 7 −1.0077295E−024.9201423E−03 8 1.3420231E−01 −2.2707237E−02 9 7.9879480E−04−1.0608316E−04 10  4.3839237E−05 −3.6699768E−06 11  −1.2244325E−051.0668768E−06

TABLE 3 EXAMPLE 2 f = 4.252, Bf = 0.904, TL = 4.929 Si Ri Di Ndj νdj1(APERTURE ∞ −0.182 STOP) *2 1.57913 0.575 1.53391 55.89 *3 10.480640.100 *4 −8.44639 0.357 1.63351 23.63 *5 −31.42199 0.329 *6 −4.355750.350 1.53391 55.89 *7 −4.07753 0.555 *8 8.31521 0.460 1.63351 23.63 *910.16085 0.199 *10  22.84164 1.100 1.53391 55.89 *11  3.30537 0.487 12 ∞0.210 1.51633 64.14 13 ∞ 0.278 14 ∞ *ASPHERIC SURFACE

TABLE 4 EXAMPLE 2 • ASPHERIC SURFACE DATA SURFACE NUMBER KA A3 A4 A5 A62 −2.0067064E+01 2.4304795E−02 −3.5869121E−01 1.2604060E+01−8.4348129E+01 3 −5.3040892E+01 3.5554495E−02 −1.3839095E+001.5721999E+01 −1.0034790E+02 4 −3.7741227E+01 2.0068380E−01−4.9639004E+00 4.9442992E+01 −2.7242204E+02 5 −7.4035116E+018.2119109E−02 −1.4999126E+00 1.6323216E+01 −9.1958923E+01 6−2.8232655E+01 −8.4599389E−02 2.5591619E+00 −2.6721178E+01 1.3975242E+027 −1.0154537E+01 3.3556186E−02 −2.1156975E−01 −4.1384629E−013.2201652E+00 8 4.3514806E−01 6.5410207E−02 8.8070994E−02 −2.3718803E+001.0997764E+01 9 1.7199948E+00 8.0391388E−02 2.1716917E−01 −1.4230013E+003.7422125E+00 10  1.0000098E+00 1.8421427E−01 −3.1022689E−011.2616306E−01 −4.3942762E−01 11  −4.7781353E+00 2.3703256E−01−8.5897442E−01 2.0311753E+00 −3.4651474E+00 A7 A8 A9 A10 A11 23.1644197E+02 −7.4905032E+02 1.1330558E+03 −1.0605523E+03 5.5928088E+023 3.8520269E+02 −9.3178873E+02 1.4286904E+03 −1.3463658E+037.1113400E+02 4 9.1896995E+02 −1.9778878E+03 2.7297372E+03−2.3392501E+03 1.1335246E+03 5 3.0669371E+02 −6.3493849E+028.2698295E+02 −6.5936090E+02 2.9404426E+02 6 −4.4210671E+028.8731110E+02 −1.1362260E+03 8.9893647E+02 −4.0009028E+02 7−1.0176026E+01 1.7892791E+01 −1.8229623E+01 1.0328276E+01 −2.8116873E+008 −2.7166724E+01 4.0291557E+01 −3.7331047E+01 2.1260066E+01−6.8360628E+00 9 −6.2089898E+00 6.5345284E+00 −4.3190667E+001.7268103E+00 −3.7891095E−01 10  1.1302743E+00 −1.4112217E+009.9303140E−01 −3.9684219E−01 8.3490278E−02 11  3.7980314E+00−2.6376193E+00 1.1511424E+00 −3.0466142E−01 4.4435539E−02 A12 2−1.2707762E+02 3 −1.6113098E+02 4 −2.3738207E+02 5 −5.6196280E+01 67.6563706E+01 7 2.3512264E−01 8 9.5190460E−01 9 3.4787333E−02 10 −7.1630212E−03 11  −2.7215384E−03

TABLE 5 EXAMPLE 3 f = 4.471, Bf = 1.029, TL = 5.098 Si Ri Di Ndj νdj1(APERTURE ∞ −0.051 STOP) *2 1.61648 0.426 1.53390 55.95 *3 10.698620.122 *4 −8.66833 0.426 1.63320 22.00 *5 −22.94809 0.615 *6 −4.085640.442 1.53380 55.80 *7 −4.61847 0.513 *8 25.34846 0.426 1.63370 23.70 *9−16.43853 0.131 *10  9.67557 0.968 1.53380 55.80 *11  2.16154 0.490 12 ∞0.210 1.51633 64.14 13 ∞ 0.400 14 ∞ *ASPHERIC SURFACE

TABLE 6 EXAMPLE 3 • ASPHERIC SURFACE DATA SURFACE NUMBER KA A3 A4 A5 A62 −2.0399111E+01 −1.5080931E−01 4.1817736E+00 −2.7724782E+011.0855203E+02 3 −2.3234226E+01 −2.8855749E−02 2.4020639E−01−2.5978260E+00 1.5364622E+01 4 −1.6962518E+01 6.4889187E−03−9.2270249E−01 8.7419080E+00 −3.9239410E+01 5 7.7747410E−012.4695014E−02 2.2655572E−01 −3.6703280E+00 2.0997163E+01 6−2.4884995E+01 −7.2160346E−02 1.1398106E+00 −9.5103237E+00 4.0255058E+017 −9.8517703E+00 5.2672450E−02 −8.8056851E−01 3.7531051E+00−7.9927631E+00 8 7.1964372E−01 1.5096293E−01 −9.0250630E−013.7763916E+00 −7.8733650E+00 9 1.5314096E+00 1.6964960E−01 5.9229024E−01−2.1257156E+00 3.5097511E+00 10  −6.0939090E+00 −4.7753691E−022.5579418E+00 −9.8781940E+00 1.7429969E+01 11  −4.4582497E+008.9345466E−02 −2.1839063E−01 1.5000130E−01 −3.1860310E−01 A7 A8 A9 A10A11 2 −2.6050742E+02 3.8990589E+02 −3.5752760E+02 1.8491305E+02−4.1608288E+01 3 −5.4071994E+01 1.1245221E+02 −1.3627252E+028.9092254E+01 −2.4374913E+01 4 9.9384644E+01 −1.4882829E+021.3011446E+02 −6.0817619E+01 1.1571953E+01 5 −6.2164100E+011.0764871E+02 −1.0986038E+02 6.1427380E+01 −1.4537823E+01 6−1.0212847E+02 1.5773898E+02 −1.4511056E+02 7.3077360E+01 −1.5508644E+017 7.5313013E+00 −9.3205095E−01 −3.9074258E+00 2.9457456E+00−6.6860172E−01 8 9.0470617E+00 −6.5197999E+00 3.1716234E+00−1.0081708E+00 1.5517560E−01 9 −4.2320760E+00 3.5736859E+00−1.8717390E+00 5.3238217E−01 −6.2309570E−02 10  −1.8006331E+011.1501301E+01 −4.4665654E+00 9.6742484E−01 −8.9727034E−02 11 5.5706477E−01 −4.6715733E−01 2.0116544E−01 −4.3499506E−02 3.7554466E−03

TABLE 7 EXAMPLE 4 f = 5.001, Bf = 0.922, TL = 5.264 Si Ri Di Ndj νdj1(APERTURE ∞ −0.051 STOP) *2 1.50265 0.479 1.53488 56.00 *3 62.841220.102 *4 −4.65230 0.357 1.62944 22.32 *5 −62.84120 0.665 *6 −3.446300.434 1.53159 48.52 *7 −4.97115 0.540 *8 63.87308 0.408 1.63384 23.85 *9−7.72007 0.400 *10  −1551.12714 0.957 1.53001 55.52 *11  2.07812 0.49012 ∞ 0.210 1.51633 64.14 13 ∞ 0.294 14 ∞ *ASPHERIC SURFACE

TABLE 8 EXAMPLE 4 • ASPHERIC SURFACE DATA SURFACE NUMBER KA A3 A4 A5 A62 −2.0393385E+01 0.0000000E+00 4.6155373E−01 6.3952076E+00−5.1657655E+01 3 1.4749796E+01 0.0000000E+00 −3.9781896E−013.5858473E+00 −1.2479043E+01 4 −1.6988894E+01 0.0000000E+00−7.7500953E−01 1.4109543E+01 −1.0201158E+02 5 −6.1399323E−010.0000000E+00 6.2071961E−01 −5.5760436E+00 3.0807794E+01 6−2.5191963E+01 0.0000000E+00 −1.3572849E−01 1.7896768E+00 −1.0351979E+017 −9.6916796E+00 0.0000000E+00 5.4297853E−01 −5.0803588E+002.6408076E+01 8 −1.0000090E+00 0.0000000E+00 1.5046502E+00−5.0715311E+00 8.9068483E+00 9 1.0277684E+00 0.0000000E+00 3.1293715E+00−1.3774007E+01 3.5155122E+01 10  −5.0050819E+00 0.0000000E+001.9172571E+00 −6.8947240E+00 9.9320815E+00 11  −4.4950700E+000.0000000E+00 2.4782257E−01 −5.3286149E−01 −1.1279628E+00 A7 A8 A9 A10A11 2 1.8487589E+02 −3.4274618E+02 2.0110827E+02 4.4860493E+02−1.0162969E+03 3 1.2034724E+01 5.0965547E+01 −1.9996888E+022.9216975E+02 −1.4993019E+02 4 4.1450244E+02 −9.9445990E+021.3629345E+03 −1.0472744E+03 1.3162399E+03 5 −1.0202767E+022.2629397E+02 −3.6072304E+02 4.1638139E+02 −3.0269488E+02 62.5477607E+01 −3.2723816E+01 1.8136512E+01 9.5684172E+00 −2.6622638E+017 −8.0171826E+01 1.3605647E+02 −1.1278035E+02 8.8775166E+003.7445177E+01 8 −5.8722239E+00 −8.7806441E+00 2.1175893E+01−1.5244031E+01 1.3665905E+00 9 −5.8084945E+01 6.1762108E+01−4.1493069E+01 1.7535586E+01 −6.1135106E+00 10  −5.5484581E+00−2.3062705E+00 5.2058091E+00 −2.8663739E+00 4.0604155E−01 11 4.3800209E+00 −5.8947790E+00 4.2797145E+00 −1.7068394E+00 2.5038522E−01A12 A13 A14 A15 A16 2 6.7262913E+02 2.2646986E+02 −6.0589428E+023.4536238E+02 −6.9276898E+01 3 −5.8087352E+01 −7.6037453E+002.1918674E+02 −2.1394193E+02 6.4342991E+01 4 −4.1968788E+037.9168654E+03 −7.8648318E+03 4.0308177E+03 −8.4921173E+02 56.6735221E+01 6.5433902E+01 −9.3786604E+00 −4.8137874E+01 2.2505736E+016 2.2246247E+01 −9.6363809E+00 3.5979232E+00 −2.0920269E+006.3966515E−01 7 4.4702616E+01 −1.3052670E+02 1.1177897E+02−4.4254898E+01 6.9338501E+00 8 2.2838624E+00 1.6000404E+00−2.8535245E+00 1.2618032E+00 −1.9145791E−01 9 3.7843446E+00−2.6150291E+00 1.0924734E+00 −2.3760789E−01 2.1079212E−02 10 2.4021424E−01 −1.1912938E−01 1.9725914E−02 −5.3857497E−04 −7.0684901E−0511  8.1738904E−02 −4.5724505E−02 7.9216644E−03 −3.4659111E−04−2.8703756E−05

TABLE 9 EXAMPLE 5 f = 4.441, Bf = 0.788, TL = 5.077 Si Ri Di Ndj νdj1(APERTURE ∞ −0.051 STOP) *2 1.50618 0.442 1.53000 56.51 *3 62.441510.102 *4 −4.33595 0.357 1.63158 22.12 *5 −45.45577 0.645 *6 −3.935850.479 1.53299 48.97 *7 −4.02199 0.519 *9 200.44313 0.408 1.63280 23.52*9 −6.32026 0.408 *10  59.78498 0.929 1.53071 55.39 *11  2.00873 0.49012 ∞ 0.210 1.51633 64.14 13 ∞ 0.160 14 ∞ *ASPHERIC SURFACE

TABLE 10 EXAMPLE 5 • ASPHERIC SURFACE DATA SURFACE NUMBER KA A3 A4 A5 A62 −2.0349555E+01 −1.2440732E−01 1.6446266E+00 −1.5931344E+00−1.3267204E+01 3 −1.4961993E+01 −8.6151868E−02 −3.6240310E−016.4812335E+00 −3.3076668E+01 4 −1.6756239E+01 2.2943715E−02−7.2308512E−01 6.6602347E+00 −3.0010508E+01 5 1.0000180E+00−8.5166576E−04 7.9915087E−01 −6.2886019E+00 2.6664015E+01 6−2.5278271E+01 1.4042051E−02 1.9663757E−02 −1.3667507E−01 −1.3375353E+007 −9.9609409E+00 −3.3286145E−02 2.6886190E−01 −1.6740606E+005.3317950E+00 8 1.0000180E+00 −3.7461662E−02 1.6217916E+00−6.2817426E+00 1.6214001E+01 9 1.0954485E+00 1.1846004E−01 1.2614393E+00−3.1136370E+00 3.9197477E+00 10  −5.9919345E+00 −6.6890635E−022.2568839E+00 −7.8023142E+00 1.1701459E+01 11  −4.4947203E+002.9938620E−01 −1.6620430E+00 5.3024155E+00 −1.0219243E+01 A7 A8 A9 A10A11 2 6.8396791E+01 −1.5465106E+02 1.7418802E+02 −1.0153335E+021.5292970E+02 3 9.0594883E+01 −1.4573502E+02 1.1916165E+02 3.0545540E+01−2.6217119E+02 4 8.0016206E+01 −1.1964384E+02 6.2217111E+017.9493596E+01 −9.2920127E+01 5 −5.7452657E+01 4.9212139E+012.3031342E+01 −3.7953928E+01 −8.3490547E+01 6 1.5425099E+006.2096730E+00 −1.6722012E+01 1.3406255E+01 2.4753614E+00 7−1.0057990E+01 9.4393066E+00 −4.4149200E+00 5.2910623E+00 −9.1275480E+008 −2.7490892E+01 2.7491802E+01 −1.4532415E+01 3.5656716E+00−1.5499615E+00 9 −3.1794739E+00 7.4394596E−01 1.5591390E+00−1.5722390E+00 2.1363959E−01 10  −8.0811513E+00 2.9300865E−013.1580686E+00 −1.5783544E+00 −1.2693927E−01 11  1.1034241E+01−5.8263915E+00 6.2265573E−02 1.6453712E+00 −6.7058133E−01 A12 A13 A14A15 A16 2 −3.0021465E+02 4.1769591E+01 5.0211232E+02 −5.5068806E+021.8130538E+02 3 5.1641300E+02 −6.9006157E+02 6.1512311E+02−3.1796483E+02 7.1017436E+01 4 −1.3809159E+02 3.6524792E+02−3.3339105E+02 1.4898119E+02 −2.7780395E+01 5 1.2277292E+026.1262583E+01 −2.0483556E+02 1.3738441E+02 −3.0892797E+01 6−1.0496919E+01 3.6615113E+00 4.3267351E+00 −4.0715487E+00 9.9486521E−017 3.7305349E+00 5.9707038E+00 −7.8442822E+00 3.6507514E+00−6.4044835E−01 8 1.1641804E+00 8.7626305E−01 −1.5751919E+007.3769819E−01 −1.1830495E−01 9 4.8369843E−01 −3.3265343E−018.6814321E−02 −7.2160320E−03 −3.6100377E−04 10  2.7309727E−01−1.8006824E−02 −3.7426765E−02 1.2353966E−02 −1.2123586E−03 11 −1.5189509E−01 2.1880053E−01 −8.0214804E−02 1.3701835E−02 −9.3547099E−04

TABLE 11 EXAMPLE 6 f = 5.383, Bf = 0.889, TL = 5.352 Si Ri Di Ndj νdj1(APERTURE ∞ −0.051 STOP) *2 1.49515 0.528 1.52999 56.56 *3 60.771840.199 *4 −4.84638 0.357 1.62053 23.49 *5 −43.29513 0.699 *6 −2.993190.434 1.59391 49.91 *7 −6.53278 0.507 *9 50.46015 0.408 1.63400 23.46 *9−7.51004 0.408 *10  593.76473 0.923 1.53001 56.22 *11  2.08206 0.490 12∞ 0.210 1.51633 64.14 13 ∞ 0.260 14 ∞ *ASPHERIC SURFACE

TABLE 12 EXAMPLE 6 • ASPHERIC SURFACE DATA SURFACE NUMBER KA A3 A4 A5 A62 −2.0389432E+01 0.0000000E+00 −1.0267663E−01 1.7897563E+01−1.5159801E+02 3 −2.3463409E+01 0.0000000E+00 −3.9041210E−014.0052266E+00 −2.1148635E+01 4 −1.6964387E+01 0.0000000E+00−2.2175122E−01 3.3423785E+00 −1.7454682E+01 5 −1.0000090E+000.0000000E+00 5.6854527E−01 −3.4226924E+00 1.0402560E+01 6−2.5208594E+01 0.0000000E+00 7.8860175E−02 4.7868189E−01 −7.5572534E+007 −9.6721497E+00 0.0000000E+00 3.4790043E−01 −9.8298115E−01−2.5860640E−01 8 −1.0000090E+00 0.0000000E+00 1.5584533E+00−5.1194578E+00 8.3678644E+00 9 1.0000738E+00 0.0000000E+00 2.7189080E+00−1.0777028E+01 2.3377037E+01 10  −6.0939090E+00 0.0000000E+001.7935727E+00 −7.1108136E+00 1.1171314E+01 11  −4.4701750E+000.0000000E+00 3.3246433E−01 −1.6285435E+00 2.2207558E+00 A7 A8 A9 A10A11 2 6.6286415E+02 −1.6976750E+03 2.4194257E+03 −1.2223569E+03−1.3828394E+03 3 6.2289021E+01 −9.4538981E+01 2.5529698E+011.3316391E+02 −1.4192396E+02 4 5.0919604E+01 −8.9729985E+011.2285240E+02 −2.2875514E+02 4.5505375E+02 5 −1.1133571E+012.1500607E+01 −2.2710694E+02 9.1107123E+02 −1.8285964E+03 62.0822296E+01 −2.6658282E+01 2.8305679E+01 −4.7548393E+01 5.9054836E+017 4.6994403E+00 −1.2069102E+01 1.6303110E+01 −6.7045527E+00−1.0690993E+01 8 −5.1432685E+00 −7.3674345E+00 1.5742200E+01−7.0947737E+00 −6.2743200E+00 9 −3.1810995E+01 2.5731143E+01−9.6217351E+00 −1.8332456E+00 3.7127490E+00 10  −7.9572204E+004.5223696E−01 3.4692255E+00 −2.7055463E+00 1.0735499E+00 11 −1.1847462E+00 −9.6421125E−02 4.1762268E−01 −1.4875831E−01−3.5185903E−02 A12 A13 A14 A15 A16 2 1.8260521E+03 1.0723277E+03−3.3053621E+03 2.3423952E+03 −5.8111471E+02 3 −1.1347952E+023.2141734E+02 −2.3939069E+02 6.6971227E+01 −2.6703722E+00 4−5.3679205E+02 2.1209090E+02 1.9053377E+02 −2.3237645E+02 7.0636574E+015 2.0581302E+03 −1.2579251E+03 3.0914362E+02 4.7146969E+01−2.9547676E+01 6 −1.8823966E+01 −3.5248371E+01 4.2435823E+01−1.8290064E+01 2.8466940E+00 7 1.4065130E+01 −2.5050978E+00−4.9360364E+00 3.3044009E+00 −6.4158617E−01 8 7.3922937E+00−9.2086714E−01 −1.9938065E+00 1.0908279E+00 −1.7764775E−01 9−1.8038088E+00 5.5403288E−01 −1.7220626E−01 4.7747960E−02 −6.1655701E−0310  −3.3573962E−01 1.1700521E−01 −3.4085774E−02 5.3854310E−03−3.0259102E−04 11  3.5722896E−02 −4.6193567E−03 −2.6225916E−039.5957509E−04 −9.4718795E−05

TABLE 13 VALUES IN CONDITIONAL EXPRESSIONS EXPRESSION CONDITIONALEXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE NUMBER EXPRESSION 1 2 34 5 6 1 f/f345 −0.51 −0.44 −0.56 −1.02 −0.55 −1.50 2 (R4f + R3r)/(R4f −R3r) 0.67 0.34 0.69 0.86 0.96 0.77 3 f1/f3 0.02 0.04 −0.04 −0.12 0.01−0.30 4 (R3f − R3r)/(R3f + R3r) −0.002 0.03 −0.06 −0.18 −0.01 −0.37 5 f· tanω/R5r 1.70 0.86 1.50 1.66 1.44 1.64 6 f/f5 −0.84 −0.58 −0.82 −1.28−1.13 −1.36 7 f/f1 1.27 1.25 1.27 1.74 1.53 1.87 8 f/f3 0.02 0.05 −0.05−0.21 0.01 −0.55

What is claimed is:
 1. An imaging lens consisting of, in order from an object side, five lenses of: a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side; a second lens that has a negative refractive power and has a meniscus shape which is concave toward the object side; a third lens that has a meniscus shape which is convex toward the image side; a fourth lens that has a positive refractive power and is convex toward the object side; and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.
 2. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −2<f/f345<−0.25  (1), where f is a focal length of a whole system, and f345 is a composite focal length of the third to fifth lenses.
 3. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: 0.2<(R4f+R3r)/(R4f−R3r)<1.6  (2), where R3r is a paraxial radius of curvature of an image side surface of the third lens, and R4f is a paraxial radius of curvature of an object side surface of the fourth lens.
 4. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −0.5<f1/f3<1  (3), where f1 is a focal length of the first lens, and f3 is a focal length of the third lens.
 5. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −0.5<(R3f−R3r)/(R3f+R3r)<0.3  (4), where R3f is a paraxial radius of curvature of an object side surface of the third lens, and R3r is a paraxial radius of curvature of the image side surface of the third lens.
 6. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: 0.5<f·tan ω/R5r<10  (5), where f is a focal length of a whole system, ω is a half angle of view, and R5r is a paraxial radius of curvature of the image side surface of the fifth lens.
 7. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −2<f/f5<−0.2  (6), where f is a focal length of a whole system, and f5 is a focal length of the fifth lens.
 8. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: 0.8<f/f1<2.5  (7), where f is a focal length of a whole system, and f1 is a focal length of the first lens.
 9. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −0.8<f/f3<0.3  (8), where f is a focal length of a whole system, and f3 is a focal length of the third lens.
 10. The imaging lens, as defined in claim 1, further comprising an aperture stop that is disposed on the object side of an object side surface of the second lens.
 11. The imaging lens, as defined in claim 1, wherein the third lens has a positive refractive power.
 12. The imaging lens, as defined in claim 1, wherein the third lens has a negative refractive power.
 13. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −1.8<f/f345<−0.3  (1-1), where f is a focal length of a whole system, and f345 is a composite focal length of the third to fifth lenses.
 14. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: 0.25<(R4f+R3r)/(R4f−R3r)<1.3  (2-1), where R3r is a paraxial radius of curvature of the image side surface of the third lens, and R4f is a paraxial radius of curvature of the object side surface of the fourth lens.
 15. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −0.4<f1/f3<0.3  (3-1), where f1 is a focal length of the first lens, and f3 is a focal length of the third lens.
 16. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −0.4<(R3f−R3r)/(R3f+R3r)<0.15  (4-1), where R3f is a paraxial radius of curvature of the object side surface of the third lens, and R3r is a paraxial radius of curvature of the image side surface of the third lens.
 17. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: 0.7<f·tan ω/R5r<3  (5-1), where f is a focal length of a whole system, ω is a half angle of view, and R5r is a paraxial radius of curvature of the image side surface of the fifth lens.
 18. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: −1.5<f/f5<−0.4  (6-1), where f is a focal length of a whole system, and f5 is a focal length of the fifth lens.
 19. The imaging lens, as defined in claim 1, wherein the following conditional expression is further satisfied: 1<f/f1<2  (7-1), where f is a focal length of a whole system, and f1 is a focal length of the first lens.
 20. An imaging apparatus comprising: the imaging lens, as defined in claim
 1. 